A bundle of optical fibers in present day endoscopes permit remote visual examination of a surgical site while a surgical procedure is being performed. During surgery, blood, tissue or other bodily material from the surgical site can splatter onto the viewing end of the endoscope and obscure the field of view through the endoscope. In some instances, it is necessary to remove the endoscope from the surgical site to clean its viewing end. This process usually interrupts and undesirably prolongs the surgical procedure. Because of the inconvenience of removing and cleaning an endoscope during surgery, some surgeons prefer to use a sheath over the endoscope that allows for flushing away any surgical debris that obscures the view through the endoscope.
Known endoscope sheaths, such as shown in U.S. Pat. Nos. 4,991,565 and 4,974,480, are usually custom fitted to the endoscope. The sheath can include tubes for air, water and suction to flush away or suction out surgical debris from the viewing end of the endoscope. The irrigation, suction and air tubes on the endoscope sheath add significant width to the profile of the endoscope and, therefore, require an incision of corresponding size to accommodate the endoscope and sheath.
Disposable sheaths for medical endoscopes that have a low profile and are designed to flush debris from the viewing end of the endoscope are described in PCT published applications WO 95/02988 and WO 94/28782. Endoscope sheaths are used to clean the tip of endoscopes such as the Endoscrub sold by Xomed. However, these devices are not satisfactory because they have a tendency to leave water on the viewing end of the endoscope which can obstruct the surgeon's vision. Other devices that attempted to solve this problem include a product known as the Richard Wolf Suction/Irrigation Sheath which is large and unwieldy.
It would be desirable to provide and endoscope sheath cleaning system that allows for the cleaning of the end of an endoscope during surgery by supplying a controlled amount of irrigation fluid to the end of the lens and to then remove the fluid. It would also be desirable to provide an endoscopic sheath cleaning system that supplies a controllable irrigation stream for irrigating the surgical field.